Polypropylene/Layered Double Hydroxide (LDH) Nanocomposites: Influence of LDH Particle Size on the Crystallization Behavior of Polypropylene

Abstract

Highly dispersed isotactic polypropylene (iPP) nanocomposites were prepared by incorporating two different sized Mg-Al LDH nanoparticles with different loadings from 1 to 10 wt % using a modified solvent mixing method. Larger sized LDH nanoparticles (∼3-4 μm) were prepared from the gel form of Mg-Al LDH, and the smaller sized nanoparticles (∼50-200 nm) were prepared by sonication of as-synthesized LDH particles. Such obtained LDH nanoparticles were carefully characterized using wide-angle X-ray diffraction (WAXD), transmission electron microscopy, and scanning electron microscopy. WAXD and atomic force microscopy results indicate that the LDH nanoparticles were highly dispersed in the iPP matrix. The influence of LDH nanoparticles size and concentration on the thermal stability, spherulitic morphology, melting behavior, isothermal crystallization kinetics, and lamellar structure of iPP were investigated. Incorporation of low loadings of sonicated LDH particles (e.g., 1-2.5 wt %) show substantial effect on thermal stability, spherulite size, crystallinity, and crystallization half-time and lamellar morphology of iPP compared to the pure iPP and that of nanocomposites with larger LDH particles with same loadings. The better nucleation ability of iPP in the presence of sonicated LDH can be attributed to the high surface area of LDH nanoparticles along with its better dispersibility within the polymer matrix. The incorporation of LDH nanoparticles does not change the crystallization growth mechanism and crystal structure of iPP.

Synthesis and Characterization of Polystyrene (PS)/Modified Ni‐Al LDH Nanocomposite: Role of Composition, Modifier and Synthesis Route of Layered Double Hydroxides (LDH)

“…It was understood that the LDH particle has broken down and dispersed uniformly onto the polystyrene matrix due to ultrasonication assisted nanocomposite synthesis. The results observed in the present study is in accordance with the literature, where the ultrasonication leads to breakage of LDH layers into smaller particles, whose lateral dimensions were changed from micrometer range to nanometer range …”

Dual Fire Retardant Action: The Combined Gas and Condensed Phase Effects of Azo-Modified NiZnAl Layered Double Hydroxide on Intumescent Polypropylene

“…For C-LDH and N-LDH, the bending vibration of the interlayer water is also reflected in the peaks at 1626 and 1631 cm -1 , respectively 42 . The characteristic band for interlayer carbonate and nitrate can be observed at 1384 and 1380 cm -1 , respectively 43 . The disappearance of the peak of carbonate and the appearance of the peak of nitrate suggest that the In the spectrum of Azo-DBA, a broad and strong peak at 2550-3200 cm -1 can be assigned to the -COOH groups, and the strong peak at 1687 cm -1 is associated with the C=O vibration 44 .…”

Structure and crystallization behaviour of syndiotactic polystyrene/layered double hydroxide nanocomposites

“…Very recently, Wang and O'Hare reported a novel method to prepare delaminated dry powders; however, application of such powders is still in its infancy. On the other hand, there are only a few reports on the exfoliation of LDHs and polymer/LDH exfoliated nanocomposites using SF‐LDHs by the solvent mixing method . Wang et al reported an aqueous miscible organic solvent treatment (AMOST) method for the preparation of exfoliated polypropylene/LDH nanocomposites by solution mixing.…”

“…The primary requirement of their approach is the stability of the LDHs after AMOST and the solubility of the polymer in the non‐polar solvent that was used for the dispersion of the LDHs. Very recently, we used a modified solution mixing method for the preparation of highly dispersed polypropylene/LDH nanocomposites using two differently sized LDHs …”